This invention relates to a safety extension with an adjustable mount which may be attached to a ladder, rigidly mounted in a fixed position, leading into a manhole, or the like. More particularly, this invention relates to a a safety extension with an adjustable mount, the safety extension of the type which may be extended to provide a safety rail for ingress and egress to and from a manhole or like below level passageway.
There are a number of prior art devices which are directed to providing for increased ladder use safety. In general, some of the devices provide a rail or auxiliary support so that the ladder user can grasp the rail and thus improve his balance and stability while using the ladder. Some prior art devices also essentially extend the useful extent of the ladder by providing a support means at the upper extremes of the ladder or the manhole.
The ladders which are commonly employed in manholes, hatchways, below level passageways, and other similar restricted passageways are frequently rigidly mounted in a fixed position with respect to the entranceway. The use of such ladders present a number of practical problems especially with respect to safety, that may not be present with other more conventional ladders. Generally, the fixed ladder may be mounted in such a way that the ladder is wholly confined within the manhole or passageway as opposed to extending through the entrance to the manhole or passageway. Such a ladder orientation necessarily presents an abnormally awkward maneuver for the user in the initial and final stages of interaction with the ladder. For example, when descending from ground level into a manhole, it is usually necessary for the user to seek the support of either an auxiliary structure above the street level or a second individual to prevent accidental falling or slipping during the initial descending process. The latter situation is exacerbated by the not infrequent case where the ladder user is also transporting tools and various working materials to the manhole. It is, therefore, readily apparent that a safety device for use in connection with a manhole ladder should be constructed of rugged materials to withstand heavy duty use. The safety device necessarily, when employed in an environment such as a manhole, should, at a minimum, be capable of extension when being used and of retraction to a position below street level when not in use. It can also be seen that a safety device which is capable of relatively easy extension and retraction may obviate the need for a second individual to assist the first individual in descending into the manhole.
While there have been attempts to adapt safety devices to the specific requirements of a fixed ladder or the walls of a manhole, the prior art is deficient with respect to devices specifically suitable for use in a manhole environment. The deficiencies of the prior art are particularly manifest in safety devices and similar apparati which are neither particularly adaptable to be constructed of rugged materials nor easy to operate. Many of the safety devices adapted for fixed ladders are overly complicated, unsafe, and neither efficient in operation nor easy to attach to the manhole ladder or manhole. The attachment of prior safety devices to these fixed ladders has proved to be both time consuming and burdensome due to the fact that the ladders may have varying rung spacings and rung diameters which necessitates expensive, field fitting or custom hardward for specific installations.
The present invention provides a new and improved safety extension particularly adapted for use in connection with manholes and ladders, which represents an advance over prior art safety devices by virtue of the rugged material construction and the adjustable means of attachment.